Magnetic microspheres based on pectin coated by chitosan towards smart drug release.

This study reports the preparation of microspheres of pectin and magnetite nanoparticles coated by chitosan to encapsulate and deliver drugs. Magnetic-pectin microspheres were obtained by ionotropic gelation followed by polyelectrolyte complexation with chitosan. Characterization data show that magnetite changes the physicochemical and morphological properties of the microspheres compared to the non-magnetic samples. Using metamizole (Mtz) as a drug model, the magnetic microspheres showed appreciable encapsulation efficiency (85 %). Release experiments performed in simulated gastric (pH 1.2) and intestinal (pH 6.8) fluids suggested that the release process is pH-dependent. At pH 6.8, the Mtz release is favored achieving 75 % after 12 h. The application of an external magnetic field increased the release to 91 % at pH 6.8, indicating that the release also is magnetic-dependent. The results suggest that the magnetic microspheres based on pectin/chitosan biopolymers show the potential to be used as a multi-responsive drug delivery system.

Non-immunological toxicological mechanisms of metamizole-associated neutropenia in HL60 cells.

Metamizole is an analgesic and antipyretic, but can cause neutropenia and agranulocytosis. We investigated the toxicity of the metabolites N-methyl-4-aminoantipyrine (MAA), 4-aminoantipyrine (AA), N-formyl-4-aminoantipyrine (FAA) and N-acetyl-4-aminoantipyrine (AAA) on neutrophil granulocytes and on HL60 cells (granulocyte precursor cell line). MAA, FAA, AA, and AAA (up to 100 µM) alone were not toxic for HL60 cells or granulocytes. In the presence of the myeloperoxidase substrate H2O2, MAA reduced cytotoxicity for HL60 cells at low concentrations (<50 µM), but increased cytotoxicity at 100 µM H2O2. Neutrophil granulocytes were resistant to H2O2 and MAA. Fe2+ and Fe3+ were not toxic to HL60 cells, irrespective of the presence of H2O2 and MAA. Similarly, MAA did not increase the toxicity of lactoferrin, hemoglobin or methemoglobin for HL60 cells. Hemin (hemoglobin degradation product containing a porphyrin ring and Fe3+) was toxic on HL60 cells and cytotoxicity was increased by MAA. EDTA, N-acetylcystein and glutathione prevented the toxicity of hemin and hemin/MAA. The absorption spectrum of hemin changed concentration-dependently after addition of MAA, suggesting an interaction between Fe3+ and MAA. NMR revealed the formation of a stable MAA reaction product with a reaction pathway involving the formation of an electrophilic intermediate. In conclusion, MAA, the principle metabolite of metamizole, increased cytotoxicity of hemin by a reaction involving the formation of an electrophilic metabolite. Accordingly, cytotoxicity of MAA/hemin could be prevented by the iron chelator EDTA and by the electron donors NAC and glutathione. Situations with increased production of hemin may represent a risk factor for metamizole-associated granulocytopenia.

Understanding the dipyrone oxidation allying electrochemical and computational approaches.

Electroanalytical methodology by boron-doped diamond electrode (BDDE) associated to the square-wave voltammetry (SWV) for the determination of hydrolyzed dipyrone (DIP) in commercial formulations, raw natural waters and in human urine was developed. Through cyclic voltammetry (CV), it was shown that the oxidation of the DIP on the BDDE was irreversible with diffusional control. Computational studies suggested that the oxidation mechanism of DIP occurred with participation of two electrons and one proton. The analytical curves were obtained for concentrations of DIP ranging from 1.0 × 10-6 to 6.5 × 10-5 mol L-1 (r = 0.9994). The values of detection limit (LOD) and quantification limit (LOQ) of DIP were calculated from SWV and found to be 2.6 × 10-7 mol L-1 and 8.8 × 10-7 mol L-1. The methodology was effectively applied to real samples with the values of calculated recoveries varying between 91.0% and 117.3% and validated by iodometric titration experiments whose values were between 93.3% and 106.9%. The proposed methodology with BDDE represents an alternative tool and it has advantageous, such as very easy handling, low cost, no need for modification, low detection limit. Furthermore, it can be used for the routine analysis of DIP in different real samples.

Paramagnetism and Fluorescence of Zinc(II) Tripyrrindione: A Luminescent Radical Based on a Redox-Active Biopyrrin.

The ability of bilins and other biopyrrins to form fluorescent zinc complexes has been known for more than a century; however, the exact identity of the emissive species remains uncertain in many cases. Herein, we characterize the hitherto elusive zinc complex of tripyrrin-1,14-dione, an analogue of several orange urinary pigments. As previously observed for its Pd(II), Cu(II), and Ni(II) complexes, tripyrrindione binds Zn(II) as a dianionic radical and forms a paramagnetic complex carrying an unpaired electron on the ligand π-system. This species is stable at room temperature and undergoes quasi-reversible ligand-based redox chemistry. Although the complex is isolated as a coordination dimer in the solid state, optical absorption and electron paramagnetic resonance spectroscopic studies indicate that the monomer is prevalent in a tetrahydrofuran solution. The paramagnetic Zn(II) tripyrrindione complex is brightly fluorescent (λabs = 599 nm, λem = 644 nm, ΦF = 0.23 in THF), and its study provides a molecular basis for the observation, made over several decades since the 1930s, of fluorescent behavior of tripyrrindione pigments in the presence of zinc salts. The zinc-bound tripyrrindione radical is thus a new addition to the limited number of stable radicals that are fluorescent at room temperature.

Ag-doping on ZnO support mediated by bio-analytes rich in ascorbic acid for photocatalytic degradation of dipyrone drug.

The analytes such as ascorbic acid (AA) present in Sechium edule were extracted (294 mg AA kg-1 fruit) in an aqueous media for its potential application for Ag-doping onto wurtzite ZnO. The bandgap of ZnO was decreased to 2.85 eV at the optimal Ag-loading of 1.18% (w/w) against 3.13 eV for the control catalyst without using the analytes and, the commercial AA only could reduce the bandgap to 2.91 eV. The saturation photo-electrochemical current density (46.68 mA cm-2) at Eanode ≥ 0.31 V vs. Ag/AgCl was almost double than pristine ZnO under visible light illumination (λmean = 525 nm, 18 K lux) and, the current density was insignificant in the dark. The doped catalyst exhibited the maximum 79.5% degradation (71% COD removal) of an anti-analgesic drug, dipyrone (100 µg L-1 dipyrone, catalyst 100 mg L-1) resulted from the formation of O2•- radical (g-factor of 2.002-2.008) and paramagnetic oxygen vacancies (g-factor of 2.020) and, no effect of dye-sensitization was noted. The highest quantum yield was found to be 34.7%. The catalyst loss was 6% after the fourth cycle and the dipyrone degradation was reduced to 70.8%.

Chitosan/waste coffee-grounds composite: An efficient and eco-friendly adsorbent for removal of pharmaceutical contaminants from water.

Waste coffee-grounds (WCG), a poorly explored source of biocompounds, were combined with chitosan (Cs) and poly(vinyl alcohol) (PVA) in order to obtain composites. Overall, WCG showed a good interaction with the polymeric matrix and good dispersibility up to 10 wt-%. At 5 wt-% WCG, the composite exhibited a noticeable enhancement (from 10 to 44%) of the adsorption of pharmaceuticals (metamizol (MET), acetylsalicylic acid (ASA), acetaminophen (ACE), and caffeine (CAF)) as compared to the pristine sample. The highest removal efficiency was registered at pH 6 and the removal followed the order ASA > CAF > ACE > MET. For all pharmaceuticals, the adsorption kinetics was found to follow the pseudo-second order model, while the adsorption mechanism was explained by the Freundlich isotherm. Reuse experiments indicated that the WCG-containing composite has an attractive cost-effectiveness since it presented a remarkable reusability in at least five consecutive adsorption/desorption cycles.

Pharmacokinetic profiles of the active metamizole metabolites after four different routes of administration in healthy dogs.

Metamizole (MT), an analgesic and antipyretic drug, is rapidly hydrolyzed to the active primary metabolite 4-methylaminoantipyrine (MAA) and relatively active secondary metabolite 4-aminoantipyrine (AA). The aim of this study was to assess the pharmacokinetic profiles of MAA and AA after dose of 25 mg/kg MT by intravenous (i.v.), intramuscular (i.m.), oral (p.o.), and rectal (RC) routes in dogs. Six dogs were randomly allocated to an open, single-dose, four-treatment, four-phase, unpaired, crossover study design. Blood was collected at predetermined times within 24 hr, and plasma was analyzed by a validated HPLC-UV method. Plasma concentrations of MAA and AA after i.v., i.m., p.o., and RC administrations of MT were detectable from 5 (i.v. and i.m.) or 30 (p.o. and RC) min to 24 hr in all dogs. The highest concentrations of MAA were found in the i.v., then i.m., p.o., and RC groups. Plasma concentrations of AA were similar for i.v., i.m., and RC, and the concentrations were approximately double those in the PO groups. The AUCEV/IV ratio for MAA was 0.75 ± 0.11, 0.59 ± 0.08, and 0.32 ± 0.05, for i.m., p.o., and RC, respectively. The AUCEV/IV ratio for AA was 1.21 ± 0.33, 2.17 ± 0.62, and 1.08 ± 0.19, for i.m., p.o., and RC, respectively. Although further studies are needed, rectal administration seems to be the least suitable route of administration for MT in the dog.

Dissolution studies of metamizole sodium and pseudoephedrine sulphate dosage forms - comparison and correlation of electronic tongue results with reference studies.

This work reports a critical evaluation of the results of the release of active substances (APIs) from novel pharmaceutical formulations provided by an electronic tongue system (ET). Detailed dissolution studies of modified-release granules used in pharmacotherapy containing metamizole sodium and pseudoephedrine sulphate were carried out. The impact of the dissolution-modifying excipients (carmellose sodium and hypromellose) on the dissolution process as well as on the outcomes of the sensor array of ion-selective electrodes was investigated. The obtained dissolution profiles were compared and correlated with those registered during the reference studies performed according to the pharmacopoeial method. It was pointed out that the proper evaluation of the efficiency of the release modification requires the examination of dosage forms as well as physical mixtures of API and excipient. Moreover, the results obtained using potentiometric ET were complementary to the classical methodology. Their partial inconsistency, remarked during several experiments, should be interpreted with caution owing to simultaneous sensing of APIs and excipients by the sensors and their various performances (i.e. selectivity and sensitivity) towards these components.

Influence of dissolution-modifying excipients in various pharmaceutical formulations on electronic tongue results.

The overall performance of a potentiometric electronic tongue (ET) as well as the sensitivity and selectivity pattern of particular ion-selective electrodes forming the array towards exemplary APIs (metamizole sodium, pseudoephedrine sulphate) and excipients (hypromellose, carmellose, Eudragit E) was determined. Simultaneous sensing of both API and the encapsulating excipient in their physical mixture was noticed using potentiometric sensors. Usually, such altering of chemical image is treated as an evidence of taste masking/modified release effect (linked with chemical entrapment of API in polymer matrix), while the observed "mixture effect" can also take place which may complicate the interpretation of ET results. Moreover, the influence of the same excipients on chemical images of various APIs was compared and related to sensor array performance. The presented considerations should be taken into account in the case of ET assessment of drug dissolution profiles and detection of modified release effect, especially when novel drug delivery systems are considered.

Pharmacokinetic profiles of the active metamizole metabolites in healthy horses.

Metamizole (MT) is an analgesic and antipyretic drug labelled for use in humans, horses, cattle, swine and dogs. MT is rapidly hydrolysed to the active primary metabolite 4-methylaminoantipyrine (MAA). MAA is formed in much larger amounts compared with other minor metabolites. Among the other secondary metabolites, 4-aminoantipyrine (AA) is also relatively active. The aim of this research was to evaluate the pharmacokinetic profiles of MAA and AA after dose of 25 mg/kg MT by intravenous (i.v.) and intramuscular (i.m.) routes in healthy horses. Six horses were randomly allocated to two equally sized treatment groups according to a 2 × 2 crossover study design. Blood was collected at predetermined times within 24 h, and plasma was analysed by a validated HPLC-UV method. No behavioural changes or alterations in health parameters were observed in the i.v. or i.m. groups of animals during or after (up to 7 days) drug administration. Plasma concentrations of MAA after i.v. and i.m. administrations of MT were detectable from 5 min to 10 h in all the horses. Plasma concentrations of AA were detectable in the same range of time, but in smaller amounts. Maximum concentration (Cmax ), time to maximum concentration (Tmax ) and AUMC0-last of MAA were statistically different between the i.v. and i.m. groups. The AUCIM /AUCIV ratio of MAA was 1.06. In contrast, AUC0-last of AA was statistically different between the groups (P < 0.05) with an AUCIM /AUCIV ratio of 0.54. This study suggested that the differences in the MAA and AA plasma concentrations found after i.m. and i.v. administrations of MT might have minor consequences on the pharmacodynamics of the drug.

Pharmacokinetic investigations of the marker active metabolites 4-methylamino-antipyrine and 4-amino-antipyrine after intramuscular injection of metamizole in healthy piglets.

Metamizole (MT) is a pyrazolone nonsteroidal anti-inflammatory drug labelled for humans and animals. The aim of this study was to assess the pharmacokinetics of its active metabolites 4-methylamino-antipyrine (MAA) and 4-amino-antipyrine (AA) in male piglets after a single intramuscular injection of MT. Eight healthy male piglets were administered MT (100 mg/kg) intramuscularly. Blood was sampled at scheduled time intervals, and drug plasma concentrations evaluated by a validated HPLC method. MAA and AA plasma concentrations were quantitatively detectable from 0.25 to 48 h and 0.50 to 72 h, respectively, in 6 of 8 and 7 of 8 animals. The average maximum concentrations of MAA and AA were of 47.59 and 4.94 mg/mL, respectively. The average half-lives were 8.57 and 13.3 h for MAA and AA, respectively. This study showed that the amount of MAA and AA produced in piglets is different to that in the animal species previously investigated. Further studies are necessary to understand whether these differences in MAA and AA plasma concentrations between animal species necessitate diverse therapeutic drug dosing.

Do pediatric medicines induce topographic changes in dental enamel?

The purpose of the present study was to evaluate the effect of common pediatric liquid medicines on surface roughness and tooth structure loss and to evaluate the pH values of these medicines at room and cold temperatures in vitro. Eighty-four bovine enamel blocks were divided into seven groups (n = 12): G1-Alivium®, G2-Novalgina®, G3-Betamox®, G4-Clavulin®, G5-Claritin®, G6-Polaramine® and G7-Milli-Q water (negative control). The pH was determined and the samples were immersed in each treatment 3x/day for 5 min. 3D non-contact profilometry was used to determine surface roughness (linear Ra, volumetric Sa) and the Gap formed between treated and control areas in each block. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were also performed. The majority of liquid medicines had pH ≤ 5.50. G1, G4, and G5 showed alterations in Ra when compared with G7 (p < 0.05). According to Sa and Gap results, only G5 was different from G7 (p < 0.05). Alteration in surface was more evident in G5 SEM images. EDS revealed high concentrations of carbon, oxygen, phosphorus, and calcium in all tested groups. Despite the low pH values of all evaluated medicines, only Alivium®, Clavulin®, and Claritin® increased linear surface roughness, and only Claritin® demonstrated the in vitro capacity to produce significant tooth structure loss.

Do pediatric medicines induce topographic changes in dental enamel?

Abstract The purpose of the present study was to evaluate the effect of common pediatric liquid medicines on surface roughness and tooth structure loss and to evaluate the pH values of these medicines at room and cold temperatures in vitro. Eighty-four bovine enamel blocks were divided into seven groups (n = 12): G1-Alivium®, G2-Novalgina®, G3-Betamox®, G4-Clavulin®, G5-Claritin®, G6-Polaramine® and G7-Milli-Q water (negative control). The pH was determined and the samples were immersed in each treatment 3x/day for 5 min. 3D non-contact profilometry was used to determine surface roughness (linear Ra, volumetric Sa) and the Gap formed between treated and control areas in each block. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were also performed. The majority of liquid medicines had pH ≤ 5.50. G1, G4, and G5 showed alterations in Ra when compared with G7 (p < 0.05). According to Sa and Gap results, only G5 was different from G7 (p < 0.05). Alteration in surface was more evident in G5 SEM images. EDS revealed high concentrations of carbon, oxygen, phosphorus, and calcium in all tested groups. Despite the low pH values of all evaluated medicines, only Alivium®, Clavulin®, and Claritin® increased linear surface roughness, and only Claritin® demonstrated the in vitro capacity to produce significant tooth structure loss.

In vitro interference by acetaminophen, aspirin, and metamizole in serum measurements of glucose, urea, and creatinine.

OBJECTIVE: Here we aimed to investigate the in vitro effects of three analgesic-antipyretic drugs frequently used in clinical practice in Mexico - acetaminophen (AAP), aspirin (ASA) and metamizole (MMZ) - on serum measurements of glucose, urea, and creatinine. DESIGN AND METHODS: Each analyte was measured in a base-serum pool spiked with the drugs at subtherapeutic, therapeutic, and toxic doses. Serum glucose and urea were measured using the hexokinase/G-6PDH and urease/GLDH kinetic assays, respectively. Serum creatinine (SCr) was measured with a Jaffe procedure based on the alkaline-picrate reaction and with an enzymatic dry-chemistry system. Measurements were carried out in IL-Monarch and Vitros DT60-II analyzers, respectively. Data were analyzed by the difference-paired interference test and by ANOVA. RESULTS: By the kinetic Jaffe/Monarch procedure, we found positive interference by the drugs on the SCr measurements and by only ASA for urea measurement. For creatinine measurements, the total errors (TEs) were 22-51%, 18-105%, and 15-26% for AAP, ASA, and MMZ respectively, while for urea measurement the TE was 16-21% for ASA. A negative interference by MMZ on SCr (TE=-47%), but no-interference for AAP or ASA, were found via the enzymatic/DT60-II system. CONCLUSIONS: In vitro positive interference induced by AAP, ASA, and MMZ (via the alkaline-picrate reaction), or negative interference by MMZ (via a dry-chemistry system), on the SCr measurements highlights the importance of investigating all possible sources of variation that may alter the accuracy of the laboratory tests, in order to provide useful results for making medical decisions for optimal patient care.

Crystal structure, DFT, spectroscopic and biological activity evaluation of analgin complexes with Co(ii), Ni(ii) and Cu(ii).

Reaction of analgin (NaL) with Co(ii), Ni(ii) and Cu(ii) salts in ethanol affords complexes of the type [ML2], which were characterized by elemental analysis, FT IR, UV-Vis, EPR, TG/DTA, magnetic susceptibility and conductance measurements. The copper(ii) complex crystallizes in the orthorhombic Pbca space group. Analgin behaves as a mono-negatively tridentate ligand via pyrazolone O, sulfonate O and tertiary amino groups. The interaction of the tertiary nitrogen with M(n+) ions is the main factor which determines the stability of complexes as revealed from natural bond orbital analysis data, where the binding energy of [ML2] decreases with an increase in the bond length of the M-N bond. Time-dependent density functional theory calculations were applied in order to realize the electronic structures and to explain the related experimental observations. The anti-bacterial activity was studied on Staphylococcus aureus and Escherichia coli. Coordination of analgin to Ni(ii) and Cu(ii) leads to a significant increase in its antibacterial activity as compared with the Co(ii) complex.

Simultaneous determination of six analgesics in human plasma using solid-phase extraction and liquid chromatography

Se desarrolló un método analítico para la determinación simultánea de paracetamol, ácido salicílico, metamizol, tramadol, ibuprofeno y diclofenaco en plasma, usando Cromatografía Líquida de Alta Resolución acoplada a un detector de array de diodos (HPLC-PDA). Se realizó una extracción en fase sólida (SPE) con cartuchos Oasis HLB®. Después de acondicionar los cartuchos con acetato de etilo, metanol y tampón fosfato pH 4, e introducir la muestra de plasma, los analitos fueron eluídos con acetato de etilo; el extracto se evaporó a sequedad, se redisolvió en fase móvil y se inyectaron 30 μL en el cromatógrafo. La separación cromatográfica fue realizada usando una columna XBridgeTM Shield RP18 (250x4.6 mm id, 5 μm tamaño partícula), y la elución se hizo con una fase móvil, compuesta por acetonitrilo, tampón fosfato pH 6,0 y agua Milli-Q, a un flujo de 1 mL/min, en modo gradiente. La respuesta del detector es lineal en el rango 0,1-20 μg/mL en plasma, con coeficientes de correlación mayores de 0.997. Los límites de detección variaron desde 7,3 a 30,1 ng/mL. Los coeficientes de variación fueron menores de 8%, y las recuperaciones oscilaron entre 90,1% para diclofenaco y 100,2% para ácido salicílico. Finalmente, se aplicó el método a 16 muestras de plasma procedentes de sujetos intoxicados con uno o más analgésicos (AU)

An analytical method for the simultaneous determination of paracetamol, salicylic acid, metamizol, tramadol, ibuprofen and diclofenac in plasma, using High Performance Liquid Chromatography with a photodiode array detector (HPLC-PDA) was developed. A solid-phase extraction (SPE) using Oasis HLB® cartridges was applied. After conditioning the cartridges with ethyl acetate, methanol and phosphate buffer pH 4, and introducing the plasma sample, the analytes were eluted with ethyl acetate. Then, the eluate was evaporated to dryness, reconstituted in mobile phase, and 30 μL were injected into the chromatograph. The chromatographic separation was performed on an XBridgeTM Shield RP18 column (250x4.6 mm id, 5 μm particle size), and the elution was carried out with a mobile phase consisting of acetonitrile, 5mM phosphate buffer pH 6 and Milli-Q water, at a flow of 1 mL/min, in gradient mode. The response of the detector was linear within the concentration range of 0.1-20 μg/mL in human plasma, with coefficients of correlation higher than 0.997. The limits of detection ranged from 7.3 to 30.1 ng/mL. The coefficients of variation were less than 8%, and the recoveries oscillated between 90.1% for diclofenac and 100.2% for salicylic acid. Finally, the method was applied to 16 plasma samples from subjects poisoned with one o more analgesics (AU)

Importance of MS selectivity and chromatographic separation in LC-MS/MS-based methods when investigating pharmaceutical metabolites in water. Dipyrone as a case of study.

Pharmaceuticals are emerging contaminants of increasing concern because of their presence in the aquatic environment and potential to reach drinking-water sources. After human and/or veterinary consumption, pharmaceuticals can be excreted in unchanged form, as the parent compound, and/or as free or conjugated metabolites. Determination of most pharmaceuticals and metabolites in the environment is commonly made by liquid chromatography (LC) coupled to mass spectrometry (MS). LC coupled to tandem MS is the technique of choice nowadays in this field. The acquisition of two selected reaction monitoring (SRM) transitions together with the retention time is the most widely accepted criterion for a safe quantification and confirmation assay. However, scarce attention is normally paid to the selectivity of the selected transitions as well as to the chromatographic separation. In this work, the importance of full spectrum acquisition high-resolution MS data using a hybrid quadrupole time-of-flight analyser and/or a suitable chromatographic separation (to reduce the possibility of co-eluting interferences) is highlighted when investigating pharmaceutical metabolites that share common fragment ions. For this purpose, the analytical challenge associated to the determination of metabolites of the widely used analgesic dipyrone (also known as metamizol) in urban wastewater is discussed. Examples are given on the possibilities of reporting false positives of dypirone metabolites by LC-MS/MS under SRM mode due to a wrong assignment of identity of the compounds detected.

High-performance liquid chromatographic assay for metamizol metabolites in rat plasma: application to pharmacokinetic studies.

In order to evaluate the pharmacokinetics of metamizol in the presence of morphine in arthritic rats, after subcutaneous administration of the drugs, an easy, rapid, sensitive and selective analytical method was proposed and validated. The four main metamizol metabolites (4-methylaminoantipyrine, 4-aminoantipyrine, 4-acetylaminoantipyrine and 4-formylaminoantipyrine) were extracted from plasma samples (50-100µl) by a single solid-phase extraction method prior to reverse-phase high performance liquid chromatography with diode-array detection. Standard calibration graphs for all metabolites were linear within a range of 1-100µg/ml (r(2)≥0.99). The intra-day coefficients of variation (CV) were in the range of 1.3-8.4% and the inter-day CV ranged from 1.5 to 8.4%. The intra-day assay accuracy was in the range of 0.6-9.6% and the inter-day assay accuracy ranged from 0.9 to 7.5% of relative error. The lower limit of quantification was 1µg/ml for all metabolites using a plasma sample of 100µl. Plasma samples were stable at least for 4 weeks at -20°C. This method was found to be suitable for studying metamizol metabolites pharmacokinetics in arthritic rats, after simultaneous administration of metamizol and morphine, in single dose.

Investigation of the microbial degradation of phenazone-type drugs and their metabolites by natural biofilms derived from river water using liquid chromatography/tandem mass spectrometry (LC-MS/MS).

The degradation of the pharmaceuticals phenazone and metamizole, two pyrazolone-derivates in widespread use, using biofilms created by natural organisms from the national park Unteres Odertal, Germany, were investigated. An analytical method based on LC-MS/MS was optimised to determine the substances phenazone and methylaminoantipyrine (MAA), the hydrolysis product of metamizole (also known as dipyrone), as well as their metabolites 1,5-dimethyl-1,2-dehydro-3-pyrazolone (DP), acetaminoantipyrine (AAA), formylaminoantipyrine (FAA) and 4-aminoantipyrine (AA). Performance characteristics of the method were evaluated in terms of recovery, standard deviation, coefficient of variation, method detection limits (MDL) and method quantification limits (MQL). Degradation studies of phenazone and MAA were conducted using a laboratory-scale continuous flow biofilm reactor fed with different nutrient media and with variable hydraulic retention times of 24 and 32 h. MAA was degraded rapidly to FAA and AA, while phenazone was not degraded under the prevailing conditions even after 32 h. By operating the bioreactor in batch mode to study the phenazone degradation potential of the biofilm under limiting nutrient conditions, an elimination rate of 85% phenazone was observed, but because of the slow elimination rate and aerobic conditions, the metabolite DP was not detected. In additional batch experiments using bacterial isolates from the natural biofilm to decompose phenazone, some bacterial strains were able to form DP from phenazone in marginal concentrations over the sampling period of eight weeks. Obviously, the microorganisms need a reasonably long time to adapt their metabolisms to enable the removal of phenazone from water samples.

Singlet oxygen scavenging activity of non-steroidal anti-inflammatory drugs.

It has long been known that singlet oxygen ((1)O2) is generated during inflammatory processes. Once formed in substantial amounts, (1)O2 may have an important role in mediating the destruction of infectious agents during host defense. On the other hand, (1)O2 is capable of damaging almost all biological molecules and is particularly genotoxic, which gives a special relevance to the scavenging of this ROS throughout anti-inflammatory treatments. Considering that the use of non-steroidal anti-inflammatory drugs (NSAIDs) constitutes a first approach in the treatment of persistent inflammatory processes (due to their ability to inhibit cyclooxygenase), a putative scavenging activity of NSAIDs for (1)O2 would also represent a significant component of their therapeutic effect. The aim of the present study was to evaluate the scavenging activity for (1)O2 by several chemical families of NSAIDs. The results suggested that the pyrazole derivatives (dipyrone and aminopyrine) are, by far, the most potent scavengers of (1)O2 (much more potent compared to the other tested NSAIDs), displaying IC(50)-values in the low micromolar range. There was a lack of activity for most of the arylpropionic acid derivatives tested, with only naproxen and indoprofen displaying residual activities, as for the oxazole derivative, oxaprozin. On the other hand, the pyrrole derivatives (tolmetin and ketorolac), the indolacetic acid derivatives (indomethacin, and etodolac), as well as sulindac and its metabolites (sulindac sulfide and sulindac sulfone) displayed scavenging activity in the high micromolar range. Thus, the scavenging effect observed for dipyrone and aminopyrine will almost certainly contribute to their healing effect in the treatment of prolonged or chronic inflammation, while that of the other studied NSAIDs may have a lower contribution, though these assumptions still require further in vivo validation.